Method for filling a wafer through-VIA with a conductive material

ABSTRACT

A method for filling a via formed through a silicon wafer is disclosed. The method entails mounting the silicon wafer on a mounting substrate and depositing either molten or solid balls of a conductive material into the via. The deposited conductive material may be reflowed to provide electrical contact with other components on the surface of wafer.

FIELD OF INVENTION

[0001] This invention relates generally to semiconductor wafermanufacture, and more particularly to methods for providing anelectrical contact from one surface of a silicon wafer to the oppositesurface, more particularly to methods for filling a through-via in asilicon wafer with a conductive material.

BACKGROUND OF THE INVENTION

[0002] A method is needed to make the most direct electrical connectionfrom an interconnect's contact tip to the substrate upon which theinterconnect is mounted. Currently, electrical continuity from aninterconnect contact tip to the mounting substrate is by use of thinfilm aluminized traces that are wire bonded to the substrate. However,inductance, capacitance, and resistance increase with trace length andcan degrade the electrical performance of the interconnect.Additionally, wire bond loop height must be kept at very low profileabove the interconnect chip to prevent the wire bonds from touching thedevice under test.

[0003] A more direct and robust electrical contact from the interconnectcontact tip to the mounting substrate would be to form a via in thevicinity of the interconnect contact tip through the full thickness ofthe wafer to the underside of the wafer. However, due to the thicknessof the wafer, and/or the high aspect ratio of the via, conventionalplating of the sides of such a “through-via” with metal is notpractical, requiring other means of filling the via. A hallmark of thisinvention is to provide a process for filling a through-via that isformed through the thickness of a wafer with a conductive material.

SUMMARY OF THE INVENTION

[0004] The invention disclosed is a process for filling a through-viathat is formed through the full thickness of a semiconductor wafer. Inone embodiment, the process comprises the steps of: (i) providing asilicon wafer with at least one through-via formed through the thicknessof the wafer; (ii) mounting the silicon wafer to a mounting substrate;(iii) positioning a solder jet nozzle in line with the through-via; and(iv) extruding a liquid conductive material through the solder jetnozzle such that the conductive material fills the through-via to form aconductive via.

[0005] In another embodiment, the process comprises the steps of: (i)providing a silicon wafer with at least one through-via; (ii) mountingthe silicon wafer onto a surface of a mounting substrate, the mountingsubstrate surface having at least one cavity, wherein the silicon waferis positioned with the through-via located in line with the cavity;(iii) positioning a solder jet nozzle in line with the through-via; and(iv) extruding a liquid conductive material through the solder jetnozzle such that the conductive material fills the through-via and thecavity in the mounting substrate to form a conductive via.

[0006] A further embodiment of the invention is a process comprising thesteps of: (i) providing a silicon wafer with at least one through-via;(ii) mounting the silicon wafer onto a surface of a mounting substratewherein the mounting substrate comprises a circuit substrate, themounting substrate surface having at least one interconnect, wherein thesilicon wafer is positioned such that the through-via is located in linewith the interconnect; (iii) positioning a solder jet nozzle in linewith the through-via; and (iv) extruding a liquid conductive materialthrough the solder jet nozzle such that the conductive material fillsthe through-via in electrical contact with the interconnect.

[0007] Another embodiment of the invention is a process comprising thesteps of: (i) providing a silicon wafer with at least one through-via;(ii) mounting the silicon wafer to a mounting substrate; (iii) providinga one or more conductive material balls; (iv) depositing the one or moreconductive material balls in the through-via by means of a vacuum nozzleor tube, such that sufficient conductive material is deposited in thevia to fill the via; and (v) reflowing the conductive material in thethrough-via to form a conductive via.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Preferred embodiments of the invention are described below withreference to the following accompanying drawings, which are forillustrative purposes only. Throughout the following views, referencenumerals will be used in the drawings, and the same reference numeralswill be used throughout the several views and in the description toindicate same or like parts.

[0009]FIG. 1 is a cross-section of a conventional silicon wafer having athrough-via formed therethrough.

[0010]FIG. 2 is a cross-section of an assembly consisting of the siliconwafer of FIG. 1 mounted to a mounting substrate showing an optionalcavity in the mounting substrate.

[0011]FIG. 3 shows the assembly of FIG. 2 at a processing stepsubsequent to that in FIG. 2.

[0012]FIG. 4 shows the wafer of FIG. 2 at a processing step subsequentto that shown in FIG. 3.

[0013]FIG. 5 is a cross sectional view of an assembly comprising thesilicon wafer of FIG. 1 mounted on a mounting substrate showing anoptional contact pad on the mounting substrate.

[0014]FIG. 6 shows the assembly of FIG. 5 at a processing stepsubsequent to FIG. 5.

[0015]FIG. 7 shows the assembly of FIG. 5 at a processing stepsubsequent to that shown in FIG. 6.

[0016]FIG. 8 shows the assembly of FIG. 2 at a processing stepsubsequent to FIG. 2.

[0017]FIG. 9 shows the assembly of FIG. 8, and a vacuum nozzledepositing balls of conducting material in an embodiment of the methodof the invention, whereby the silicon wafer is heated while the balls ofthe conductive material are deposited.

[0018]FIG. 10 shows the assembly of FIG. 5 at a processing stepsubsequent to FIG. 5.

[0019]FIG. 11 shows the assembly of FIG. 10, and a vacuum nozzledepositing balls of conductive material in an embodiment of the methodof the invention whereby the wafer is heated while depositing of theballs of conducting material.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] In the following detailed description, references made to theaccompanying drawings which form a part hereof, and in which is shown byway of illustration specific embodiments in which the invention may bepracticed. These embodiments are described in sufficient detail toenable those skilled in the art to practice the invention, and it is tobe understood that other embodiments may be utilized and thatstructural, logical and electrical changes may be made without departingfrom the spirit and scope of the present invention.

[0021] The terms “wafer” or “substrate” used in the followingdescription include any semiconductor-based structure having a siliconsurface. Wafer and substrate are to be understood as includingsilicon-on-insulator (SOI) or silicon-on-sapphire (SOS) technology,doped and undoped semiconductors, epitaxial layers of silicon supportedby a base semiconductor foundation, and other semiconductor structures.Furthermore, when references made to a wafer or substrate in thefollowing description, previous process steps may have been used to formregions or junctions in the base semiconductor structure or foundation.

[0022] The term “interconnect” refers to a device for making anelectrical connection. Such devices include, inter alia, contacts,wires, electrically conductive pathways as well as more complicatedstructures.

[0023]FIG. 1 shows an exemplary silicon wafer 10, having a conventionalthickness of about 28 mil, which can be about 8 to about 32 mil. In oneexample of a wafer suitable for use in this invention, an 8 in, diameterwafer having a thickness of 28 mil is fabricated and then background toa thickness of about 12,5 mil. The wafer includes a contact opening orvia hole 11 which has been formed through the entire thickness of thewafer. Preferably, the via hole 11 has a diameter (width) of at leastabout 4 mil up to about 12 mil, preferably up to about 6 mil.

[0024] The wafer 10 comprises a first surface 80 and a second surface 81which are generally opposed to each other. Typically, first surface 80includes at least one interconnect 82 mounted thereon. A typicalinterconnect 82 is an interconnect for testing a semiconductor wafer.Such an interconnect 82 includes a substrate (not shown), conductivevias in the substrate (not shown), and first and second contacts (notshown) on either side of the conductive vias for making temporaryelectrical connectons between the wafer and test circuitry. Morepreferably interconnect 82 is in electrical contact with via hole 11.The electrical contact may be by any means but is typically by means ofa metallized trace(s), preferably an aluminum or copper trace.Optionally, the second surface 81 of wafer 10 comprises metallizedtraces or pads (not shown) that act as capture pads to increase orenhance the conduction between the via 11 and the substrate 12.

[0025] The through-via can be formed in the wafer by laser machining,such as disclosed in copending U.S. patent application Ser. No.09/475,546, filed Dec. 20, 1999, incorporated herein by reference. Themethod of U.S. patent application Ser. No. 09/475,546, generally stated,comprises laser machining conductive vias for interconnecting contactson a component, using a laser beam that is focused to produce a desiredvia geometry. A via having an hour glass geometry (not shown) can beproduced by focusing the laser beam proximate to a midpoint of the via.The hour glass geometry includes enlarged end portions having increasedsurface areas for depositing a conductive material into the via, and forforming contacts on the via. A via having an inwardly tapered geometry(not shown) can be produced by focusing the laser beam proximate to anexit point of the beam from the substrate. A via having an outwardlytapered geometry can be produced by focusing the laser beam proximate toan entry point of the beam into the substrate. A representative diameterof the via hole formed by the method of U.S. patent application Ser. No.09/475,546 is from about 10

m to about 2 mils or greater. A representative fluence of the laser beamsuitable for forming such a via hole through an about 28-mil thick,silicon wafer is from about 2 to about 10 watts/per opening at a pulseduration of about 20-25 ns, and at a repetition rate of up to severalthousand per second. The wavelength of the laser beam can be a standardinfrared or green wavelength (e.g., 1064 nm-532 nm), or any wavelengththat will interact with and heat silicon.

[0026] As shown in FIG. 2, the wafer 10 is mounted to a substrate thatfunctions to hold the wafer in a specified position, such as mountingsubstrate 12. Mounting substrate 12 can be an assembly chuck to containthe solder within the via hole during the process of this invention, orcould be a circuit substrate to which the traces of the silicon wafer 10are to be electrically connected. Optionally, mounting substrate 12 mayinclude a cavity 15 in the surface 22 over which the wafer is mounted,as shown in FIG. 2. When mounting substrate 12 includes a cavity 15,wafer 10 is mounted so that cavity 15 is in line with the through-viahole 11. The cavity 15 in mounting substrate 12 provides a containmentarea in which excess solder protrudes from silicon wafer 10 to allow thesilicon wafer 10 to be surface mounted to a substrate. In other words,the presence of cavity 15 provides for the formation of a solder bump 24on the second surface 81 of the silicon wafer 10.

[0027] Referring to FIG. 3, after silicon wafer 10 is mounted tomounting substrate 12, a device for depositing balls of liquidconductive material is positioned over the mounted wafer 10. Typically,the device for depositing balls of liquid conductive material comprisesa solder jet nozzle 13. As shown in FIG. 3, the solder jet 13 ispositioned in line with through-via hole 11. A molten conductivematerial 14 is then supplied to solder jet nozzle 13. The moltenconductive material may be solder or an uncured conductive polymer,preferably solder.

[0028] The conductive material 14 is readily wettable to the substrate'smetallized trace materials along with the metallized traces of thecontact substrate. The term “readily wettable” means that the materialmakes good electrical and mechanical contact. The conductive material 14can comprise any suitable readily wettable material, such as a solderalloy, typically a lead/tin (Pb/Sn), lead/tin/silver (Pb/Sn/Ag), orindium/tin (In/Sn) alloy. Example solder alloys include, inter alia, 95%Pb/5% Sn, 60% Pb/40% Sn, 63% In/37% Sn, or 62% Pb/36% Sn/2% Ag.Alternately, the conductive material 14 can comprise a relatively hardmetal such as nickel, copper, beryllium copper, alloys of nickel, alloysof copper, alloys of beryllium copper, nickel-cobalt-iron alloys andiron-nickel alloys. In addition, the conductive material 14 can comprisea conductive polymer such as a metal-filled silicone, a carbon filledink, or an isotropic or anisotropic adhesive in an uncured free-flowingstate.

[0029] Next, the molten conductive material is forced through solder jetnozzle 13 to form an extrudate. Preferably, the extrudate comprisessmall molten balls that are preferably about 25-125 μm in diameter. Thesolder jet nozzle 13 is aligned with through-via 11 and one or moremolten balls 26 are deposited into through-via 11, as shown in FIG. 3. Asufficient quantity of molten conductive material 14 is extruded throughsolderjet nozzle 13 and into via 11 to at least fill through-via 11 Inthe case where mounting substrate 12 comprises a cavity 15, the quantityof molten conductive material extruded through solder jet nozzle 13 issufficient to fill both the cavity 15 and the through-via 11, as shownin FIG. 4. The conductive material deposited into through-via 11 willeventually solidify as it cools to form filled via 28 and solder bump24.

[0030] A preferred method of providing the balls 26 of molten conductivematerial 14 is through the use of solder jet technology modified fromink jet printing technology. One suitable example of this is solder jettechnology available from MicroFab which is based on piezoelectricdemand-mode ink-jet printing technology (i.e., piezoelectric pressureinducer) and is capable of placing molten solder droplets, 25-125micrometers in diameter, at rates up to 400/sec (not shown). Operatingtemperatures of 220° C. are normally used, and temperatures up to 300°C. have been feasible.

[0031] Another suitable solder jet device is disclosed in U.S. Pat. No.6,082,605, incorporated herein by reference. The solder jet apparatusdisclosed in U.S. Pat. No. 6,082,605 (not shown) is a continuous-modesolder jet that includes a blanking system and a raster scan system. Ingeneral, the solder droplets are formed from melted metal held in liquidreserve. A temperature controller is connected to the liquid metalreservoir to maintain the liquid metal held in the reservoir at adesired temperature that facilitates optimum droplet formation andrelease. The solder droplets are formed by the application of thedriving pressure at a sufficient vibration force. The driving pressureis be provided by a pressure inducer, which is comprised of apiezoelectric crystal driven by a tuning frequency sufficient to causepressure to build up in the liquid metal reservoir. The mechanicalvibration is generated by a vibrator, which comprises a secondpiezoelectric crystal driven by another tuning frequency, which causesthe liquid metal reservoir to vibrate. Once the solder droplets areformed, the vibration releases the droplets from the liquid metalreservoir and the force of gravity draws the droplets down on apredictable velocity. The solder jet nozzle 13 is opened and closed bymeans of a solenoid.

[0032] Optionally, the conductive material filling in via 28 can bereflowed to wet any connections located on the first surface 80 or thesecond surface 81 of the wafer, such as interconnect 82.

[0033] The deposition of the balls of conductive material 14, andoptional reflow of the conductive material, is preferably performed inan inert atmosphere such as nitrogen, especially when the conductivematerial 14 comprises solder. Such an inert environment reduces theformation of metal oxides, some of which can increase the electricalresistance of the interconnects. Alternatively, if the deposition orreflow process is conducted in an ambient atmosphere, a shielding gas,such as nitrogen, can be directed around the extruding nozzle. Themolten solder balls 14 would then be shielded from possible oxidation asthey travel from the nozzle into the via.

[0034] In another embodiment, mounting substrate 12 can comprise acircuit substrate (not shown) to which interconnect 82 is to beelectrically connected, and which comprises at least one metal contactpad 16, as shown in FIG. 5. Metal pad 16 may comprise a conductivemetal, such as copper or gold. Conveniently, metal pad 16 comprises goldto enhance solderability to the pad. In the case where mountingsubstrate 12 comprises a copper contact pad 16, silicon wafer 10 ispreferably mounted so that copper contact pad 16 is in line withthrough-via hole 11.

[0035] In a preferred embodiment, the circuit substrate of mountingsubstrate 12 comprises the testing circuitry of a testing apparatus. Thetesting apparatus can be, for example, a conventional wafer probehandler, or a probe tester, modified for use with filled via 28. Waferprobe handlers, and associated test equipment, are commerciallyavailable, for example, from Electroglass, Advantest, Teradyne,Megatest, Hewlett-Packard, and others.

[0036] Next, solder jet 13 deposits balls 26 of molten conductivematerial 14 are deposited into via hole 11, as shown in FIG. 6. Theballs 26 of molten conductive material 14 are deposited as previouslydescribed.

[0037] The molten conductive material 14 is then allowed to cool,resulting in a filled via 28 as shown in FIG. 7. Optionally, theconductive material 14 within filled via 28 can be reflowed to wet thetop and bottom connections such as interconnect 82.

[0038] In another embodiment of the method of the invention, a siliconwafer 10 is provided having a through-via hole 11, as shown in FIG. 1.The wafer 10 is mounted onto mounting substrate 12 as shown in FIG. 2.The mounting substrate 12 can be, for example, an assembly chuck tocontain the solder during fabrication, or a circuit substrate to whichtraces on the wafer 10 are to be electrically connected.

[0039] Optionally, the mounting substrate 12 can include one or more onecavities 15 in the surface 22 onto which the wafer 10 is mounted. Inthis option, wafer 10 is mounted such that the cavity 15 in mountingsubstrate 12 is in line with through-via hole 11. Optionally, cavity 15in mounting substrate 12 may be partially filled with conductivematerial 14 prior to mounting the wafer 10 to substrate 12. This optionadvantageously reduces the quantity of conductive material 14 that mustbe deposited by nozzle 13.

[0040] Next, one or more discrete portions 30, preferably in the shapeof balls, of a meltable conductive material 14 are provided. Theconductive material 14 may be solder or a conductive polymer, preferablysolder, as previously described.

[0041] Next, a vacuum nozzle or tube 113 of a vacuum device is used totransfer a ball 30 of conductive material 14 to the opening ofthrough-via hole 11, as shown in FIG. 8. Using the vacuum nozzle or tube113, the ball 30 of conductive material 14 into via hole 11. The depositmay be made either by placing, dropping or pressing the ball 30 into viahole 11. These steps are continued until sufficient balls 30 ofconductive material 14 are deposited into via hole 11 to provide enoughconductive material 14 to fill via hole 11. In the case where mountingsubstrate 12 comprises a cavity 15, the process is continued untilsufficient balls 30 are deposited into via hole 11 to provide enoughconductive material to at least fill cavity 15 and via hole 11. Asstated above, advantageously cavity 15 is partially filled withconductive material 14 prior to mounting wafer 10 to substrate 12.

[0042] The vacuum nozzle or tube 113 is preferably a component of avacuum pick-and-place system. Vacuum pick-and-place systems have beenused to deposit solder balls in the semi conducting industry and anysuch system may be suitable for use in this invention. One such methodis disclosed in U.S. Pat. No. 5,788,143, the disclosure of which isincorporated by reference herein, which discloses an apparatuscomprising a reservoir for containing solder particles, means forproducing a vacuum, a pick-up head having a connection for the vacuumproducing member and a plurality of apertures smaller in size than thesolder particles, a control member causing the head to transport theparticles from the reservoir, a member for aligning the apertures andmember for controlling the vacuum to the pick-up head. Another system istaught in U.S. Pat. No. 5,088,639, the disclosure of which isincorporated by reference herein, which discloses a multipoint solderingprocess in which a vacuum pick-up tool attached to a robot gripper andsimultaneously picks up a plurality of solder balls from an oscillatingreservoir. A vision system determines that each pickup element has asolder ball, then the balls are dipped in sticky flux and deposited ontoa circuitboard and interconnection locations by releasing the vacuum.Furthermore, U.S. Pat. No. 4,462,534, the disclosure of which isincorporated herein by reference, describes a suction device, whichsuctions up moving solder balls and contains a vibrating ball anddispenses the balls to a previously fluxed substrate.

[0043] Next, heat is applied to the wafer 10 mounted on the mountingsubstrate 12 in order to melt the balls 30 of conductive material 14 andcause the conductive material 14 to reflow, thereby forming filled via28 and wetting any contact metalization on the upper surface 80 andlower surface 81 of the wafer 10, such as interconnect 82 as shown inFIG. 4.

[0044] Optionally, as shown in FIG. 9, the silicon wafer 10 may beheated while the balls 30 of conductive material 14 are deposited intovia hole 11, thereby melting and reflowing the conductive material 14 asthe balls 30 are deposited.

[0045] Optionally, the melting and reflow of conductive material 14occurs under an ambient atmosphere or under a shielding gas as describedfor embodiment one. This option is particularly advantageous when theconductive material 14 comprises solder.

[0046] In another embodiment of the method of the invention, mountingsubstrate 12 comprises a circuit substrate (not shown) to which theinterconnect 82 of silicon wafer 10 is to be electrically connected, andcomprises at least one copper pad 16 as shown in FIG. 5. Wafer 10 ismounted to mounting substrate 12 such that the copper pad 16 is in linewith through-via hole 11.

[0047] Next, one or more discrete particles, preferably in the form ofballs 30 of a meltable conductive material 14 is provided. Theconductive material 14 may be solder or a conductive polymer aspreviously described. Balls 30 typically have a diameter of about 25 toabout 125 microns.

[0048] Next, a vacuum nozzle or tube 113 of a vacuum device, such as thepick-and-place systems described earlier, is used to transfer a ball 30of conductive material 14 to the opening of through-via 11 as shown inFIG. 10. Vacuum nozzle or tube 113 is used to deposit the ball 30 ofconductive material 14 into via hole 11. The deposit may be made eitherby placing, dropping or pressing the ball into via hole 11. These stepsare continued until sufficient balls 30 of conductive material 14 aredeposited into via hole 11 to provide enough conductive material 14 tofill via hole 11.

[0049] Next, heat is applied to the wafer 10 mounted on the mountingsubstrate 12 in order to melt the balls 30 of conductive material 14 andcause the conductive material 14 to reflow thereby forming filled via 28and wetting any contact metalization such as interconnect 82 on theupper surface 80 and lower surface 81 of the wafer as shown in FIG. 4.

[0050] Optionally, as shown in FIG. 11, the silicon wafer 10 may beheated while the balls 30 of conductive material 14 are deposited intovia hole 11, thereby melting and reflowing the conductive material 14 asthe balls 30 are deposited.

[0051] In compliance with the statute, the invention has been describedin language more or less specific as to structural and methodicalfeatures. It is to be understood, however, that the invention is notlimited to the specific features shown and described, since the meansherein disclosed comprise preferred forms of putting the invention intoeffect. The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents.

What is claimed is:
 1. A process for filling a with a conductivematerial, the process comprising the steps of: providing a silicon waferhaving a first surface and a second surface, with at least one viaextending therethrough from the first surface to the second surface;mounting the silicon wafer to a mounting substrate; positioning a devicefor depositing balls of molten material in line with the via; andextruding a liquid conductive material through the device for depositingballs of molten material such that the conductive material fills the viato form a conductive via.
 2. The process for filling a via of claim 1wherein the silicon wafer has a thickness of at least about 6 mil. 3.The process for filling a via of claim 1, wherein the via has a diameterof at least about 10 micrometers.
 4. The process for filling a via ofclaim 1, wherein the via has a diameter up to about 15 mil.
 5. Theprocess for filling a via of claim 1, wherein the via has a diameter upto about 6 mil.
 6. The process for filling a via of claim 1, wherein thedevice for depositing balls of molten material comprises a piezoelectricpressure inducer.
 7. The process for filling a via of claim 1, whereinthe conductive material comprises solder or a conductive polymer.
 8. Theprocess for filling a via of claim 1, wherein the solder is an alloyselected from the group consisting of about 95% Pb/5% Sn, about 60%Pb/40% Sn, about 63% in/37% Sn and about 62% Pb/36% Sn/2% Ag.
 9. Theprocess for filling a via of claim 1, further comprising, after the stepof extruding the conductive material, the step of: reflowing theconductive material to fill the via.
 10. A process for filling a viawith a conductive material, the process comprising the steps of:providing a silicon wafer with at least one through-via; mounting thesilicon wafer onto a surface of a mounting substrate, the mountingsubstrate surface having at least one cavity, wherein the silicon waferis positioned such that the through-via is located in line with thecavity; positioning a solder jet nozzle in line with the through-via;and extruding a liquid conductive material through the solder jet nozzlesuch that the conductive material fills the through-via and the cavityin the mounting substrate to form a conductive via.
 11. The process forfilling a through-via of claim 10 wherein the silicon wafer has athickness of at least about 28 mil.
 12. The process for filling athrough-via of claim 10 wherein the solder jet nozzle comprises apiezoelectric pressure inducer.
 13. The process for filling athrough-via of claim 10 further comprising the step of: reflowing theconductive material to fill the via.
 14. A process for filling athrough-via with a conductive material, the process comprising the stepsof: providing a silicon wafer with at least one through-via; mountingthe silicon wafer onto a surface of a mounting substrate, the mountingsubstrate comprising a circuit substrate having at least oneinterconnect, wherein the silicon wafer is positioned such that thethrough-via is located in line with the interconnect; positioning adevice for depositing balls of molten material in line with thethrough-via; and extruding a liquid conductive material through thedevice for depositing balls of molten material such that the conductivematerial fills the through-via in electrical contact with theinterconnect.
 15. The process for filling a through-via of claim 14wherein the silicon wafer has a thickness of at least about 6 mil. 16.The process for filling a through-via of claim 14 wherein the solder jetnozzle comprises a piezoelectric pressure inducer.
 17. The process forfilling a via of claim 14, further comprising, after the step ofextruding the conductive material, the step of: reflowing the conductivematerial to fill the via.
 18. A process for filling a through-via with aconductive material, the process comprising the steps of: providing asilicon wafer having a first surface and a second surface, the firstsurface comprising at least one first interconnect with at least onevia; mounting the silicon wafer onto a surface of a mounting substrate,such that the second surface of the wafer is in contact with themounting substrate; positioning a device for depositing balls of moltenmaterial in line with the through-via; extruding a liquid conductivematerial through the device for depositing balls of molten material suchthat the conductive material fills the through-via to form a conductivevia in electrical contact with the first interconnect.
 19. The processfor filling a through-via of claim 18 wherein the silicon wafer has athickness of at least about 6 mil.
 20. The process for filling athrough-via of claim 18 wherein the solder jet nozzle comprises apiezoelectric pressure inducer.
 21. The process for filling a via ofclaim 18, further comprising, after the step of extruding the conductivematerial, the step of: reflowing the conductive material to fill thevia.
 22. A process for filling a through-via with a conductive material,the process comprising the steps of: providing a silicon wafer having afirst surface and a second surface generally opposed to each other withat least one through-via, wherein the first surface comprises anelectrical interconnect; mounting the silicon wafer onto a surface of amounting substrate such that the second surface of the silicon wafer isin contact with the surface of the mounting substrate, the mountingsubstrate surface having at least one cavity, wherein the silicon waferis positioned such that the through-via is located in line with thecavity; positioning a device for depositing balls of molten material inline with the through-via; and extruding a liquid conductive materialthrough the solder jet nozzle such that the conductive material fillsboth the through-via and the cavity in the mounting substrate and theconductive material wets the interconnect to form a conductive via. 23.The process for filling a through-via of claim 22 wherein the siliconwafer has a thickness of at least about 6 mil.
 24. The process forfilling a through-via of claim 22 wherein the solder jet nozzlecomprises a piezoelectric pressure inducer.
 25. The process for fillinga via of claim 22, further comprising, after the step of extruding theconductive material, the step of: reflowing the conductive material tofill the via.
 26. A process for filling a through-via with a conductivematerial, the process comprising the steps of: providing a silicon waferhaving a first surface and a second surface generally opposed to eachother, the first surface comprising at least one first interconnect withat least one through-via extending therethrough from the first surfaceto the second surface; mounting the silicon wafer onto a surface of amounting substrate, such that the second surface of the wafer is incontact, the mounting substrate comprising a circuit substrate themounting substrate surface having at least one second interconnect,wherein the silicon wafer is positioned such that the through-via islocated in line with the second interconnect; positioning a device fordepositing balls of molten material in line with the through-via;extruding a liquid conductive material through the device for depositingballs of molten material such that the conductive material fills the viato form a conductive via in electrical contact with the firstinterconnect and the second interconnect.
 27. The process for filling athrough-via of claim 26 wherein the silicon wafer has a thickness of atleast about 6 mil.
 28. The process for filling a through-via of claim 26wherein the solder jet nozzle comprises a piezoelectric pressureinducer.
 29. The process for filling a via of claim 26, furthercomprising, after the step of extruding the conductive material, thestep of: reflowing the conductive material to fill the via.
 30. Aprocess for filling a through-via with a conductive material, theprocess comprising the steps of: providing a silicon wafer having afirst surface and a second surface, with at least one via extendingtherethrough from the first surface to the second surface; mounting thesilicon wafer to a mounting substrate; providing a multiplicity ofconductive material balls one or more discrete portions of a conductivematerial; depositing conductive material balls in the through-via bymeans of a vacuum nozzle or tube, such that sufficient conductivematerial is deposited in the via to fill the via; and reflowing theconductive material in the through-via to form a conductive via.
 31. Theprocess for filling a through-via of claim 30 wherein the silicon waferhas a thickness of at least about 6 mil.
 32. The process for filling athrough-via of claim 30 wherein the through-via has a diameter of atleast about 10 micrometers.
 33. The process for filling a through-via ofclaim 30 wherein the via has a diameter up to about 15 mil.
 34. Theprocess for filling a through-via of claim 31 wherein the via has a sizeup to about 6 mil.
 35. The process for filling a through-via of claim 30wherein the conductive material comprises solder or a conductivepolymer.
 36. The process for filling a through-via of claim 30 whereinthe solder is an alloy selected from the group consisting of about 95%Pb/5% Sn, about 60% Pb/40% Sn, about 63% In/37% Sn and about 62% Pb/36%Sn/2% Ag.
 37. A process for filling a through-via with a conductivematerial, the process comprising the steps of: providing a silicon waferwith at least one through-via; mounting the silicon wafer onto a surfaceof a mounting substrate, the mounting substrate surface having at leastone cavity, wherein the silicon wafer is positioned such that thethrough-via is located in line with the cavity; said cavity optionallymay be presented partially filled with conductive material; providing amultiplicity of conductive material balls; depositing conductivematerial balls in the through-via by means of a vacuum nozzle or tube,such that sufficient conductive material is deposited in the via to fillthe via; and reflowing the conductive material in the through-via toform a conductive via.
 38. The process for filling a through-via ofclaim 37 wherein the silicon wafer has a thickness of at least about 6mil.
 39. A process for filling a through-via with a conductive material,the process comprising the steps of: providing a silicon wafer having afirst surface and a second surface generally opposed to each other, thefirst surface comprising at least one first interconnect with at leastone through-via; mounting the silicon wafer onto a surface of a mountingsubstrate, such that the second surface of the wafer is in contact withthe surface of the mounting substrate, the mounting substrate comprisinga circuit substrate the mounting substrate surface having at least onesecond interconnect, wherein the silicon wafer is positioned such thatthe through-via is located in line with the second interconnect;providing a multiplicity of conductive material balls; depositingconductive material balls in the through-via by means of a vacuum nozzleor tube, such that sufficient conductive material is deposited in thevia to fill the via; and reflowing the conductive material in thethrough-via such that the conductive material fills the through-via toform a conductive via in electrical contact with the first interconnectand the second interconnect.
 40. The process for filling a through-viaof claim 39 wherein the silicon wafer has a thickness of at least about6 mil.
 41. A process for filling a through-via with a conductivematerial, the process comprising the steps of: providing a silicon waferwith at least one through-via; mounting the silicon wafer onto a surfaceof a mounting substrate, the mounting substrate surface having at leastone cavity, wherein the silicon wafer is positioned such that thethrough-via is located in line with the cavity; providing a multiplicityof conductive material balls; depositing conductive material balls inthe through-via by means of a vacuum nozzle or tube, such thatsufficient conductive material is deposited in the via to fill the via;and reflowing the conductive material in the through-via such that theconductive material fills the through-via and the cavity in the mountingsubstrate to form a conductive via.
 42. The process for filling athrough-via of claim 41 wherein the silicon wafer has a thickness of atleast about 6 mil.
 43. A process for filling a through-via with aconductive material, the process comprising the steps of: providing asilicon wafer having a first surface and a second surface generallyopposed to each other with at least one through-via, wherein the firstsurface comprises an electrical interconnect; mounting the silicon waferonto a surface of a mounting substrate such that the second surface ofthe silicon wafer is in contact with the surface of the mountingsubstrate, the mounting substrate surface having at least one cavity,wherein the silicon wafer is positioned such that the through-via islocated in line with the cavity; providing a multiplicity of conductivematerial balls; depositing conductive material balls in the through-viaby means of a vacuum nozzle or tube, such that sufficient conductivematerial is deposited in the via to fill the via; and reflowing theconductive material in the through-via such that the conductive materialfills both the through-via and the cavity in the mounting substrate andthe conductive material wets the interconnect to form a conductive via.44. The process for filling a through-via of claim 43 wherein thesilicon wafer has a thickness of at least about 6 mil.
 45. A process forfilling a through-via with a conductive material, the process comprisingthe steps of: providing a silicon wafer with at least one through-via;mounting the silicon wafer onto a surface of a mounting substrate themounting substrate comprising a circuit substrate, the mountingsubstrate surface having at least one interconnect, wherein the siliconwafer is positioned such that the through-via is located in line withthe interconnect; providing a multiplicity of conductive material balls;depositing conductive material balls in the through-via by means of avacuum nozzle or tube, such that sufficient conductive material isdeposited in the via to fill the via; and reflowing the conductivematerial in the through-via such that the conductive material fills thethrough-via in electrical contact with the interconnect.
 46. The processfor filling a through-via of claim 45 wherein the silicon wafer has athickness of at least about 6 mil.
 47. A process for filling athrough-via with a conductive material, the process comprising the stepsof: providing a silicon wafer having a first surface and a secondsurface generally opposed to each other, the first surface comprising atleast one first interconnect with at least one through-via; mounting thesilicon wafer onto a surface of a mounting substrate, such that thesecond surface of the wafer is in contact, the mounting substratecomprising a circuit substrate the mounting substrate surface having atleast one second interconnect, wherein the silicon wafer is positionedsuch that the through-via is located in line with the secondinterconnect; providing a multiplicity of conductive material balls;depositing conductive material balls in the through-via by means of avacuum nozzle or tube, such that sufficient conductive material isdeposited in the via to fill the via; and reflowing the conductivematerial in the through-via such that the conductive material fills thethrough-via to form a conductive via in electrical contact with thefirst interconnect and the second interconnect.
 48. The process forfilling a through-via of claim 47 wherein the silicon wafer has athickness of at least about 6 mil.
 49. An assembly for testing siliconwafers comprising: a silicon wafer comprising a first surface and asecond surface generally opposed to each other the first surfacecomprising at least one interconnect the wafer having at least onethrough-via extending from the first surface to the second surface, thethrough-via being completely filled with a conductive material, whereinthe interconnect is electrically connected to the through-via; a testingcircuit comprising at least one contact pad; wherein the wafer ismounted on the testing circuit such that the second surface of the waferabuts the surface of the testing circuit having the contact pad whereinthe contact pad is an electrical connection with the conductive materialof the through-via.
 50. The testing apparatus of claim 49 wherein thewafer is at least about 6 mil thick.
 51. The assembly of claim 49wherein the interconnect and the through-via are electrically connectedby means of a metallized trace.
 52. The assembly of claim 51 wherein themetallized trace is an aluminum or copper trace.
 53. The assembly ofclaim 49 wherein the second surface of the wafer further comprisesmetallized traces or pads that act as capture pads.